Reusable solid rocket motor (RSRM) designs can be found in many rocketry applications, with perhaps the best-known applications involving solid rocket boosters of the Space Shuttle, or the Ares 1 rocket. The solid rocket boosters of a spacecraft may be attached to opposite sides of a main external tank of the spacecraft and, together, may furnish the majority of the thrust required to launch the spacecraft from its mobile launch platform and contribute to accelerate the vehicle to more than about 4800 km per hour (3,000 miles per hour) before detaching and separating from the external tank.
FIG. 1 is a perspective view of an example of a conventional RSRM 100 of a spacecraft vehicle. RSRM 100 comprises a plurality of detachable segments connected to each other by field joints 120 and factory joints 140. The term “field joint” is commonly used in the field of rocketry to denote joints capable of being assembled in either a factory or the field. Field joints 120 and segmented design provides maximum flexibility in transportation, handling, recovery, refurbishment, assembly, and fabrication of RSRM 100. For example, the segmenting of the solid rocket motor facilitates propellant casting procedures and permits transportation of the large segments on heavy-duty railcars incapable of carrying an assembled RSRM 100.
FIG. 2A is a partially cut-away view of a conventional RSRM comprising field joints having a pressure-actuated joint system. With reference to FIG. 2A, RSRM 100 comprises a forward segment 121, a forward-center segment 122, an aft-center segment 124, and an aft segment 126. Segments 121, 122, 124, and 126 may collectively contain a solid propellant grain structure, which is illustrated as a center-perforated propellant grain structure 145. More specifically, each of segments 121, 122, 124, and 126 houses a portion or segment of propellant grain structure 145.
FIG. 2B is a sectional view of one of the field joints shown in FIG. 2A, and in particular is a sectional view of a forward field joint 112 connecting the forward segment 121 and forward-center segment 122 of the RSRM 100 of FIG. 2A. FIG. 2C is a sectional view of another one of the field joints shown in FIG. 2A, and in particular is a sectional view of a center field joint 112a connecting the forward-center segment 122 and an aft-center segment 124 of the RSRM 100 of FIG. 2A. FIG. 2D is a sectional view of still another one of the field joints shown in FIG. 2A, and in particular is a sectional view of an aft field joint 112b connecting the aft-center segment 124 and the aft segment 126 of the RSRM 100 of FIG. 2A. FIG. 2E is a zoomed-in, enlarged view of the forward field joint 112 of FIG. 2B.
Also illustrated in FIG. 2B are inhibitors 193 and 203, each of which is shaped as an annular radial disk. With reference to FIG. 2E, inhibitors 193 and 203 are disposed on opposite sides of a channel 204, and may be applied after partial propellant cure. Inhibitors 193 and 203 may be used to thermally protect propellant grain structure 145 and control grain ignition. Inhibitors 193 and 203 may, for example, include materials such as nitrile butadiene rubber (NBR) and carboxyl-terminated polybutadiene copolymer. Inhibitors 193 and 203 may also include other ingredients, for example, fillers such as asbestos. Inhibitors 193 and 203 may be designed to bond to and cure simultaneously with propellant grain structure 145.
As propellant grain structure 145 burns, portions of inhibitors 193 and 203 that remain within an aperture of RSRM 100 may cause RSRM 100 to experience undesired oscillations. More specifically, as an example, vortex shedding from inhibitor 193 or inhibitor 203 may result in oscillations in the combustion chamber of RSRM 100 that may undesirably shake an associated orbiter. Conventionally, in an effort to better understand oscillations caused by an inhibitor within a combustion chamber of a rocket motor, real-time radiography has been utilized to monitor a shape and a position of the inhibitor. However, real-time radiography has proven to be inadequate due to slow frame rate and poor resolution.
The inventors have appreciated that there is a need for enhanced methods, systems, and devices for measuring characteristics of an object and, in particular, for methods, devices, and systems for determining a shape of an object.